In the prior art of microwave vector measurements and particularly network analyzers there has existed a problem of developing data information over a broad frequency range. To accomplish coupling of mixers, amplifiers and the like to receive the energy from the radio frequency energy source and the reflected energy from the device under test, it is well recognized that microwave systems have relatively narrow operating frequency bands over which they are effective. Therefore, to provide a broad frequency band to a device under test, the prior art provided different devices for connecting to the device under test depending upon the range of frequencies of the radio frequency signal to be applied thereto. Thus it was necessary to have a multiplicity of devices for interconnecting the radio frequency signal source and the device under test. The use of such a multiplicity of devices complicates the test apparatus set up and requires the expenditure of significant time to interconnect the device under test with the test apparatus. Also each time a different interconnecting device is inserted there is a distinct probability that re-calibration of the test apparatus should be done.
As one solution to this problem there has been developed a relatively complex network employing various transformers and other components capable of operating over a relatively wide frequency range. The prior art network, however, is quite expensive and introduces unwanted complications in taking the measurements which are required.